Cantilever bending head of a tube bending machine

ABSTRACT

The invention relates to machines for three-dimensionally bending tubes by way of pushing them into a bending head. The bending head comprises a casing with an axial passway for the tubes and bending means constituted by two coaxial discs mounted in a cantilever fashion on the casing of the head. A backup roll and a supporting roll of the bending means are arranged between the discs, while the bending roll is secured on a turnable lever set, by means of its cheeks, on the discs that are flush with the faces of the latter. The bending head features considerably smaller thickness compared with known types, which permits the bending of tubes with a limited pitch.

United States Patent 1 1 Shubin et al.

1111 3,845,648 Nov. 5, 1974 CANTILEVER BENDING HEAD OF A TUBE BENDING MACHINE g [76] Inventors: Vladimir Nikolaevich Shubin,

Pervomaiskaya ulitsa, l, kv. 103; Viktor Sergeevich Silantiev, Kastanaevskaya ulitsa, 57, korpus l, kv. 58; Alexandr Sergeevich Khlyntsev, Kolenchataya ulitsa, 4-a, kv. 8; Antonina Petrovna Barsova, Sheremetievskaya ulitsa, 67, korpus 2, kv. 5, all of Moscow, USSR.

[22] Filed: Nov. 14, 1973 [21] Appl. No: 415,660

[30] Foreign Application Priority Data Nov. 30, l972 U.S.S.R 1851659 [52 us. C1. 72/173, 72/216 [51] lnt. Cl B2ld 7/08 [58] Field of Search 72/171, 173, 166, 170, 72/216 [56] References Cited UNITED STATES PATENTS 659,936 10/1900 Morris 72/l74 X 1.0471112 12 1912 Brantigan ..72/17 3 Primary ExaminerMilton S. Mehr Attorney, Agent, or Firm-Waters, Roditi, Schwartz &

Nissen [57] ABSTRACT The invention relates to machines for threedimensionally bending tubes by way of pushing them into a bending head. The bending head comprises a casing with an axial passway for the tubes and bending means constituted by two coaxial discs mounted in a cantilever fashion on the casing of the head. A backup roll and a supporting roll of the bending means are arranged between the discs, while the bending roll is secured on a turnable lever set, by means of its checks, on the discs that are flush with the faces of the latter. The bending head features considerably smaller thickness compared with known types, which permits the bending of tubes with a limited pitch.

2 Claims, 2 Drawing Figures g The present invention relates to pressure working of -metals and more particularly to cantilever bending heads of tube bending machines intended for the spatial or three dimensional bending of tubes by way of their being pushed intoa bending head.

At the same time the invention finds application in bending heads of other machines, e.g., the coiling types.

Known in the art are cantileverbending heads of tube bending machines (cf. US. Pat. No. 3,373,587) that, comprise a casing with a through longitudinal passway for a billet (tube) to be pushed thereon. One end of the casing of the bending head is secured to the frame of the machine, while the other end carries a backup roll around which the tube is bent, and a supporting roll designed to support the'tube and assume the reaction force produced by the bending roll in the course of tube bending, the latter moves about the head casing,

both the backup roll and the supporting roll are secured in the above longitudinal passway by means of their axles.

The bending roll is secured between the cheeks (sectors) of a lever turnable in a bendingplane, said lever being hinged to the casing of the bending head as well as kinematically coupled with the machine drive.

One of the disadvantages of such bending heads is that their cantilver portion is too thick, as the cheeks of the turnable lever are secured outside the head casing and thus overlap a major part of the working zone of the machine, which restricts the operational potentialities of the latter because it does not permit to produce articles with a small bending pitch, e.g., when coiling spirals or batteries.

Moreover, the bending of tubes to a small radius results in corrugation and distortion of their crosssection, which affects the quality of the articles in general.

An object of the present invention is to provide a bending head permitting the bending of tubes to a small bending pitch.

Another object of the invention is to permit the bending of tubes to small radii without corrugation or distortion of thetube cross-sections.

These and other objects of the invention are accomplished in a cantilever bending head comprising a casing with an axial longitudinal passway for a billet (tube) and bending means constituted by a backup roll stationary about the casing, around which roll the tube is bent, a supporting roll designed to assume a reaction force developing in the course of the tube bending, and a movable bending roll secured between two parallel cheeks of a lever turnable in a bending plane and kinematically coupled with the machine drive.

According to the invention, the bending means are mounted on two coaxial discs and secured by their inner faces 'in a cantilever fashion to the outer lateral walls of the cantilever portion of the casing so that their common axis is perpendicular to the axis of the casing, the backup and supporting rolls being arranged between said discs, and that there are two coaxial through holes in the cheeks of the turnable lever,.whose diameter is made equal to the diameter of the discs and by which holes said cheeks are set on the respective discs, being flush with both of their faces.

The inventive embodiment permits to reduce the width of the cantilever portion of the bending head by superposing the surfaces of the cheeks of the rotatable lever, with the surfaces of the discs constituting an extension of the head casing.

Reduction in the width of the bending head permits to bend a tube with a smaller pitch and thus'to expand the variety of spatial articles produced by the machine, specifically, such that could so far be manufactured only through the assembly or welding of isolated pieces, e.g., spatial parts with spiral members.

lt'is recommended that a hold-down roll be provided between the discs, symmetrically with the backup roll, and mounted together 'with the supporting roll on the opposite ends of a balance arm whose axle is secured 4 in the disks.

Such embodiment permits to improve the quality of articles especially at limited bending radii by providing automatic control of the force that holds down the tube to the backup roll depending on the bending force.

The invention will be more apparent from a detailed description of an exemplary embodiment, reference being had to the annexed drawings, wherein:

FIG. 1 shows schematically a general view of the inventive cantilever bending head (with a partial axial section); and

FIG. 2 shows a section along Il-ll as in FIG. 1.

The inventive cantilever bending head comprises a casing 1 (FIG. 1) shaped as a beam with a rectangular cross-section, arranged in a horizontal plane and secured in a cantilever fashion on a frame 2 of the bending machine.

Secured to the cantilever portion of the head casing l are two vertically arranged cylindrical discs 3 and 4 (FIG. 2) coaxial with each other so that their axis is perpendicular to the axis la of the head casing 1, said discs 3' and 4, being secured to the lateral walls of the cantilever portion of the casing 1 by their inner faces.

Provided in the casing l of the head along its axis la is a through longitudinal horizontal; passway 5 for moving a billet (tube 6) to bending means mounted on the discs 3 and 4, and constituted by four parallel rolls 7,8,9- and 10: the backup 7, supporting 8, bending 9 and hold-down 10 rolls.

The tube 6 is bent around the backup roll 7 which is arranged above the axis of the passway 5 and on its own axis 11 (FIG. 2) whose ends are secured in the discs 3 and 4.

Below the axis of the passway 5 and between these discs 3 and 4 are the supporting 8 and, the hold-down l0 rolls of which the latter is mounted symmetrically about the backup roll 7.

Both of the rolls 8 and 10 are set, by means of their axles or shafts l2 and 13, on the ends of a balance arm 14 whose axle 15 is secured in the discs 3 and 4.

The bending roll 9 is set on its axle 16 secured on a turnable vertical lever 17 between two of its cheeks l8 and 19 clamped by means of a pin 20. These cheeks l8 and 19 have two coaxial through holes by which they are set on the cylindrical surfaces of the respective discs 3 and 4 with capability of rotation about them, the rotation being made possible with the aid of a hinged link 21 connected to the pin 20 and a connecting rod 22, the latter being linked, in its turn, with a drive of the bending machine (not shown).

Note should be made that the thickness of the cheeks 18 and 19 of the turnable lever 17 should be such as to prevent the protrusion of the lateral surfaces of the cheeks beyond the inner and outer faces of the discs 3 and 4, which ensures maximum thickness for the bending head in its cantilever portion.

The operation of the cantilever bending head is as follows. Together with the turnable lever 17 the bending roll 9 is imparted from the machine drive a rocking motion by means of the hinged link 21 and the connecting rod 22.

The tube 6 being pushed in a direction indicated by an arrow A (FIG. 1) (by any known technique) into the passway 5 of the casing l of the bending head at the elevated bending roll 9, the tube 6 is subjected to bending in one plane (vertical, in FIG. 1). The bending radius is inversely proportional to the elevation of the bending roll 9, while the bending angle depends on the duration of the tube being pushed at the elevated bending roll 9.

The duration of the tube 6 being pushed into a position 90, the roll 9 being lowered, determines the size of a straight portion between the bending cycles.

Variations in the plane of bending of the tube 6 are effected by turning the tube 6 into, say, position 6a, the bending roll 9 being lowered.

Spiral bending of the tube 6 into a position 6b (bending a spiral) is effected by turning the tube 6 when it is being bent.

The pitch between the spiral coils depends on the relation of the rate of pushing the tube into the head to the rate of its simultaneous turning around its own axis.

. The holding-down of the tube 6 by means of the holddown roll 10 to the backup roll 9 takes place owing to to the reaction force emerging on the supporting roll 8 in the course of bending. The force of holding down the tube 6 to the backup roll 9 varies on its own depending on the bending force, as the balance arm 14 rocks around its own axle 15.

What we claim is:

l. A cantilever bending head for tube bending machines having drive means, comprising: a casing with lateral walls and an axial, longitudinal passway for the tubes; two coaxial discs secured in a cantilever fashion to said walls by their inner faces so that the axis of said discs is perpendicular to the axis of said casing; bending means including a backuproll secured immovably between said discs on one side of said casing axis, for bending the tubes around it; a supporting roll between said discs on the other side of said casing axis, to assume a reaction force developing in the course of bending; a turnable lever adjusted to turn in a bending plane, kinematically coupled with said drive means and having two parallel cheeks which have two coaxial through holes whose diameter is equal to that of said discs, and by which holes said cheeks are set on respective ones of said discs to be flush with both of said faces; and a bending roll secured between said cheeks of the lever.

2. The bending head as defined in claim 1, further comprising a hold-down roll symmetrical to said backup roll, between said discs, and mounted together with said supporting roll on opposite ends of a balance arm whose shaft is secured on said discs. 

1. A cantilever bending head for tube bending machines having drive means, comprising: a casing with lateral walls and an axial, longitudinal passway for the tubes; two coaxial discs secured in a cantilever fashion to said walls by their inner faces so that the axis of said discs is perpendicular to the axis of said casing; bending means including a backup roll secured immovably between said discs on one side of said casing axis, for bending the tubes around it; a supporting roll between said discs on the other side of said casing axis, to assume a reaction force developing in the course of bending; a turntable lever adjusted to turn in a bending plane, kinematically coupled with said drive means and having two parallel cheeks which have two coaxial through holes whose diameter is equal to that of said discs, and by which holes said cheeks are set on respective ones of said discs to be flush with both of said faces; and a bending roll secured between said cheeks of the lever.
 2. The bending head as defined in claim 1, further comprising a hold-down roll symmetrical to said backup roll, between said discs, and mounted together with said supporting roll on opposite ends of a balance arm whose shaft is secured on said discs. 